Since the mobile phone has been given personalized business application functions, the connection between the mobile phone and external devices has become particularly important. There are three general connection methods: data cable, infrared connection and Bluetooth (wireless connection technology). The popularity of advanced Bluetooth technology on mobile phones is not enough; although infrared connection is convenient and fast, the transmission speed is slow and unstable, and only mobile phones that support infrared light can be used; so the important task of connecting with the outside is naturally derived from the data cable Take it. This is also why mobile phone players prefer the data cable.